The present invention relates to a gas turbine and, more particularly, to a gas turbine wherein air discharged from or extracted by a compressor is introduced to a turbine section to control temperatures of the turbine casing and a turbine rotor thereby maintaining an optimum gap at the tip end of the rotor blades of the gas turbine over an entire operating range so as to provide for a high efficiency operation of the gas turbine.
In, for example, Japanese Patent Laid Open Application No. 48-87212, a controlling air system is proposed wherein a portion of the air discharged from a compressor is introduced into a gas turbine for cooling the gas turbine.